If you were just watching who comes in and out of an Army basketball game you might think that you accidentally went to the wrong arena. Complete line changes make it seems like a hockey game has broken out. The Black Knights’ Zach Spiker has a 12-man rotation and it’s not uncommon to see five new players take the court at once.

The antics of his fellow Patriot League head coach Fran O’Hanlon at Lafayette aren’t quite the same. The Leopards’ head coach shuffles guys in and out seemingly at every dead ball trying to get favorable match ups on offense and defense. Beset by injuries this season O’Hanlon is trying to maximize the pieces of his depleted roster.

These are the two most extreme cases – in fact they’re more than three standard deviations away from college basketball’s mean – but every coach is constantly substituting during a college basketball. In NCAA Division I teams substitute about four times every five minutes, or an average of 32 times during a full game. It doesn’t have anything to do with team quality or pace either. It’s purely the style of the head coach that really seems to influence.

Let’s start with a simple question. How much do teams substitute during a game? Using the play-by-play logs available on the NCAA.org website I calculated the rate for each team. (*See below for the methodology.) Here’s a histogram of the rounded totals for each team.

As you can see, while the average number of substitutions is 32 times per game, the most common number of subs a team makes in a game is around 29 (22 teams). There’s more weight though towards the high end of the scale, especially due to two outliers, Army and Lafayette. Let’s look at the extremes.

Most Subs Per Game:

Army: 67.8

Lafayette: 65.7

Central Michigan: 56.8

VCU: 53.9

Eastern Illinois: 53.7

Siena: 53.5

Hartford: 51.9

Lipscomb: 49.2

Manhattan: 48.9

Bakersfield: 48.1

Fewest Subs Per Game:

Grand Canyon: 14.5

American: 15.6

Oakland: 17.5

N.C. Central: 18.4

Lamar: 18.5

Texas Southern: 18.5

East Carolina: 18.6

Fordham: 18.7

IUPUI: 19.4

Coppin St.: 19.5

Yes, the Battle of the Bronx featured two teams at complete opposite ends of the spectrum. There’s more than a 30 substitutions per game difference between Steve Masiello and Tom Pecora this season.

Pecora’s options this season though are quite limited. The Rams have been beset by injuries and don’t have that many scholarship players that Fordham feels comfortable having on the court for a long period of time. That probably plays into this number quite a bit. It’s not that Pecora doesn’t want to sub at least a little more, he just can’t. (Grand Canyon – in its first season of Division I – is another example of this phenomenon.)

On the other end of the spectrum what drives a coach to sub a ton isn’t necessarily obvious. Across Division I there’s no statistically significant relationship between tempo and the average number of substitutions. Don’t believe me? Check out this graph. The blob is super impressive.

There’s also no relationship between the number of substitutions a team makes and how good it is (at least based on pythogorean expectation). Some good teams like Syracuse, Stanford and Iowa St. don’t sub much at all. Others, such as VCU, Manhattan, Indiana St. and Indiana are in the Top 45 in terms of the number of subs they make per game and in KenPom’s Top 100. I thought that there might potentially be a bell curve – where teams in the middle of pythagorean expectation would sub quite a bit – but that fails to occur. Basically, there are coaches that play it close to the vest and coaches that want to play a ton of players at all levels of Division I. Here’s the graph showing that relationship:

Overall, it seems as if the number of substitutions a coach makes during a game is largely a matter of personal preference. One thing I have anecdotally noticed is overmatched teams scaling down their rotations in close games. For instance, St. Francis Brooklyn subs about 29 times per game, but only subbed 15 times when they were trying to upset Syracuse. I’d have to do further study to see if there’s some sweet spot where that relationship actually exists.

Army and Lafayette are two huge outliers early in the season. Still, it’s great that if Spiker and O’Hanlon want to shuffle players in and out faster than a Vegas dealer, they can. It’s a unique quality of college basketball.

*Methodology: I built a script that pulls the substitutions for each game using text parsing of the HTML play-by-play logs available on NCAA.org. Here’s the Battle of the Bronx example from earlier. Because the logs are based on StatCrew XML that’s uploaded, the wording is standardized, which makes separating the substitutions a doable endeavor. The entire process takes a few hours (there are a lot of web pages to hit). Also, due to this data collection strategy, games that haven’t been uploaded yet are (obviously) not included in the analysis. The data was as current as possible through Dec. 22 at 5 p.m. I’ve added a table below so you can see where your favorite team ranks and how many games were analyzed.